It is true that every day we see fewer modifications created by other users that allow us to change the appearance of all or some particular applications. Macnix
The modifications are made through two small applications that apply the necessary changes automatically. The procedure is simple, we download the images, mount them and execute the installers. After following the simple steps we will have our application with a “new” interface.
And I say again in quotes because in the case of Contacts it is not very noticeable. In Calendars it does earn more but there are still some aspects to be polished like the yellow excess under the letters . Anyway, it’s a first step. And you can always tinker until you get the desired modification. However, it is important that you make a backup of the original applications in case you want to go back to the original interface.
To back up your Contact and Calendar applications, simply drag them from the Applications folder to the desired location and hold down the Option (ALT) key to duplicate them.
When restoring, you must first remove the modified applications. To do this, from the Terminal we write the following command:
sudo rm -rf ApplicationsCalendar.app
For Contacto you will only have to replace Calendar with Contacts. Then, drag the backups back to the Applications folder and that’s it. Next you have the links in case you want to make the modification.